1. Field of the Invention
The present invention relates to an ink jet printing apparatus of a so-called serial type which performs a printing operation by moving a print head in a main scan direction and also moving a print medium in a subscan direction crossing the main scan direction, and more particularly to an ink jet printing apparatus capable of easily detecting the condition of use of the printing apparatus and a method of controlling the same.
2. Description of the Related Art
A common serial type ink jet printing apparatus mounts one or more print heads on a carriage that moves in the main scan direction and also removably mounts on the print heads ink tanks accommodating inks to be supplied to the respective print heads. In the ink jet printing apparatus with the ink tanks removably mounted on the print heads, when the ink tanks run out of inks, the inks can be replenished by replacing the old tanks with new tanks filled with inks, facilitating their handling on the part of user.
One conventionally known construction for removably mounting ink tanks on print heads engages a part of each ink tank in a groove formed in the associated print head. In this construction, fitting a part of each ink tank in the groove formed in the associated print head can bring a liquid supply port formed at a bottom of each ink tank into hermetic engagement with an ink receiving port that communicates with a common liquid chamber of the print head. In this type of ink jet printing apparatus, the ink tanks must engage the corresponding print heads properly for supply of ink from the ink tanks to the print heads.
To meet this requirement, conventional ink jet printing apparatus employ a detection means, such as a sensor or switch, to determine whether or not the ink tanks are properly mounted to a mounting portion of the associated print head in order to alert the user when any tank is not properly mounted.
However, such a switch or sensor detects only the mounted state of ink tanks and does not detect any other conditions. Thus, from the standpoint of cost performance, such a detection means is not normally used in relatively inexpensive apparatus. In conventional apparatus therefore, any improper mounting of an ink tank at the start of the use of the apparatus or during an ink tank replacement results in ink failing to be supplied to the associated print head, which in turn causes an ink ejection failure of the print head.
In the serial type ink jet printing apparatus., a trouble may occur in which an obstacle present in a carriage path blocks a proper movement of the carriage.
For example, the user may inadvertently start using a printing apparatus without removing a protective material inserted in the apparatus for its protection during shipping. If power is initially turned on with the protective material (obstacle) left in the carriage path, a reference position of a print head is determined at a wrong position, which prevents the print head position from being recognized correctly in subsequent printing operations. In that case, a print medium fails to be fed at a correct timing with respect to the reciprocal movement of the print head, making it impossible to produce a desired printing operation.
To reliably prevent such a trouble, it is necessary to check for any obstacle present in the carriage path by using a sensor. This sensor, however, is not normally used in inexpensive printing apparatus and the resolving of this problem is entirely left to the user's careful handling during unpacking.